It is proposed to study the hemispheric specialization of speech-related sensorimotor control systems. A dichotic pursuit tracking paradigm will be used wherein subjects match a continuously varying auditory stimulus (target) with a second stimulus (cursor) of the same sensory quality and controlled by a speech articulator. Previous results have supported the contention that the left hemisphere in normal speakers is specialized for speech movement control by possessing an auditory-sensorimotor integration mechanism that integrates speech-related auditory feedback with the kinesthetic concomitants of the motor responses producing the auditory signals. Proposed research will explore further the outer bounds of this laterality phenomenon. Specific studies will attempt to: (1) determine whether laterality effects can be shown for isometric as well as isotonic modes of control; (2) determine whether a laterality effect exists with monaural presentation of target and cursor signals; (3) determine whether subject phonation of a cursor signal will enhance a laterality effect; and (4) extend the paradigm to patient populations such as aphasics.